The present invention relates to a case system for lead batteries, a lead battery, a lead battery rack layout and an electrical cell.
Lead batteries are a common type of battery, where the electrodes are composed of lead sheets with lead or lead dioxide and the electrolyte is formed by sulfuric acid. A lead battery essentially is made up of an acid resistant case and at least two sheets of lead of which one functions as a positive, whereas the other functions as a negative electrode.
The sheets are submersed into a sulfuric acid solution.
This most generic type of lead battery is equipped with a gas opening at the top to prevent gas pressure build up. Gas pressure increases, when hydrogen and oxygen are produced through electrolysis.
Understandably such batteries can only be stored and operated in an orientation that ensures that the gas opening is on the top of the case, such as to ensure venting and prevent spilling of the acid. They require refilling with H2O on a regular basis.
One particular type of lead batteries, so called VRLA type batteries (Valve Regulated Lead Acid Battery) are sealed with a pressure regulating valve and do not require a refilling of water to keep the battery functioning.
Furthermore, such batteries can be designed with absorbent glass mats to have the acid in an absorbed state on glass fibers. These types of lead batteries have significant advantages as they can be operated in any orientation and have a reduced maintenance requirement, i.e. no refilling of H2O is necessary.
One commonly used battery design is the so-called 19 inch or 23 inch rack system battery, with the battery terminals accessible from the front. Four individual 12V batteries are arranged such as to fit a 19-inch or 23 inch wide and 400 or 600 mm deep drawer of an electrical cabinet or rack. These elements are configured such as to present the terminal accesses at the front side. Cases adapted for racks in the 19 inch/23 inch front access layout have an essentially box shaped case element with 6 compartments. The electrical cells are placed into the compartments, such as to extend too down inwardly into the compartments and to present their individual terminations on the topside.
This configuration has been found to carry a number of disadvantages. For one part, the top down arrangement of the cell leads, due to the large vertical height of the cells, to stratification of the sulfuric acid, which in turn leads to a decrease in capacity and service life of the battery.
One further disadvantage in respect to said setup is a consequence of the 2×3 arrangement of the compartments. It requires comparatively large and thick outside sidewalls of the individual cells so to keep up the compression of the absorbent glass mat between the plates, especially when operating the battery at high temperatures.
A further disadvantage is that the cabling and connection of the individual batteries in a rack is complicated and prone to short circuits.